Caption: False colour scanning electron micrograph of the synovial membrane (normal) of the knee joint. The synovial membrane forms a lining enclosing a freely moveable joint such as the knee, elbow or ankle. It produces the synovial fluid, which flows in the free space between the joint bones. It is a proteinous liquid containing many cell types such as synovial cells, monocytes, macrophages & lymphocytes. The fluid lubricates the joint & is a nutritive source for the cartilage encasing the ends of the bone. Normal synovial membrane is smooth whereas rheumatoid membrane shows numerous irregular projections cluttering the surface. Mag:X17 at 35mm size. Original is bw print p174/006.